U.S. patent application number 13/512237 was filed with the patent office on 2012-11-08 for microcapsules containing pesticide and having polyvinyl monomers as cross-linking agents.
This patent application is currently assigned to BASF SE. Invention is credited to Marc Rudolph Jung, Klaus Kolb, Tobias Joachim Koplin, Michael Krapp.
Application Number | 20120283104 13/512237 |
Document ID | / |
Family ID | 43769180 |
Filed Date | 2012-11-08 |
United States Patent
Application |
20120283104 |
Kind Code |
A1 |
Jung; Marc Rudolph ; et
al. |
November 8, 2012 |
Microcapsules containing pesticide and having polyvinyl monomers as
cross-linking agents
Abstract
The present invention relates to microcapsules comprising a
pesticide-containing capsule core and a capsule wall, and to a
process for the preparation of these microcapsules. Furthermore,
the invention relates to an agrochemical formulation comprising the
microcapsules, and to the use of the microcapsules for controlling
phytopathogenic fungi and/or undesired plant growth and/or
undesired insect or mite infestation and/or for regulating the
growth of plants.
Inventors: |
Jung; Marc Rudolph; (Worms,
DE) ; Koplin; Tobias Joachim; (Ludwigshafen, DE)
; Krapp; Michael; (Altrip, DE) ; Kolb; Klaus;
(Schifferstadt, DE) |
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
43769180 |
Appl. No.: |
13/512237 |
Filed: |
November 25, 2010 |
PCT Filed: |
November 25, 2010 |
PCT NO: |
PCT/EP2010/068245 |
371 Date: |
May 25, 2012 |
Current U.S.
Class: |
504/359 ;
424/497; 514/75 |
Current CPC
Class: |
A01N 25/10 20130101;
A01N 25/28 20130101; A01N 25/28 20130101; A01N 25/10 20130101; A01N
43/56 20130101; A01N 47/24 20130101; A01N 43/56 20130101; A01N
47/24 20130101 |
Class at
Publication: |
504/359 ;
424/497; 514/75 |
International
Class: |
A01N 25/28 20060101
A01N025/28; A01P 7/02 20060101 A01P007/02; A01P 21/00 20060101
A01P021/00; A01N 57/00 20060101 A01N057/00; A01P 13/00 20060101
A01P013/00; A01P 7/04 20060101 A01P007/04; A01P 3/00 20060101
A01P003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2009 |
EP |
09177493.5 |
Claims
1-15. (canceled)
16. An agrochemical formulation comprising microcapsules, where the
microcapsules are suspended in aqueous solution, and where the
microcapsules comprise a pesticide-containing capsule core and a
capsule wall, where the capsule wall is constructed from 30 to 90%
by weight of one or more C.sub.1-C.sub.24-alkyl esters of acrylic
acid or of methacrylic acid, acrylic acid, methacrylic acid or
maleic acid (monomers I), 10 to 70% by weight of one or more
polyvinyl monomers (monomer II), and 0 to 30% by weight of one or
more further monomers (monomer III), which are different from the
monomers I and II and which comprise at most 5.0% by weight of
divinyl monomers, in each case based on the total weight of the
monomers, where the capsule core comprises a nonpolar solvent, and
where the weight ratio of nonpolar solvent to pesticide is in the
range 1:20 to 20:1.
17. The formulation according to claim 16, where monomer III is
selected from the group consisting of itaconic acid, maleic
anhydride, 2-hydroxyethyl acrylate and methacrylate,
acrylamido-2-methylpropanesulfonic acid, methacrylonitrile,
acrylonitrile, methacrylamide, N-vinylpyrrolidone,
N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethyl
methacrylate and diethylaminoethyl methacrylate.
18. The formulation according to claim 16, where monomer I
comprises both C.sub.1-C.sub.24-alkyl esters of acrylic acid and
methacrylic acid (monomers Ia) and further comprises one or more
unsaturated C.sub.3-C.sub.4-carboxylic acid (monomers Ib).
19. The formulation according to claim 18, where the weight ratio
of monomer Ia to monomer Ib is in the range from 10:1 to 1:10.
20. The formulation according to claim 16, wherein the polyvinyl
monomer is selected from the group consisting of trimethylolpropane
triacrylate and trimethacrylate, pentaerythritol triallyl ether,
pentaerythritol tetraallyl ether, pentaerythritol triacrylate and
pentaerythritol tetraacrylate, and their technical-grade
mixtures.
21. The formulation according to claim 16, where the nonpolar
solvent is soluble in water at 20.degree. C. to at most 10% by
weight.
22. The formulation according to claim 21, where the weight ratio
of nonpolar solvent to pesticide is in the range 1:10 to 8:1.
23. The formulation according to claim 16, where the weight ratio
of capsule core to capsule wall is in the range from 50:1 to
1:1.
24. The formulation according to claim 16, where the pesticide is
present in dissolved form in the capsule core.
25. The formulation according to claim 16, where the pesticide
dissolves to give a clear solution at 25.degree. C. to at least 10
g/l in an aromatic hydrocarbon mixture with an initial boiling
point of at least 225.degree. C.
26. The formulation according to claim 16 comprising 20 to 70% by
weight of microcapsules, based on the agrochemical formulation.
27. The formulation according to claim 16, where the content of
pesticide which is present in the pesticide-containing capsule core
is 10 to 600 g per liter of agrochemical formulation.
28. A process for preparing the microcapsules according to claim
16, comprising preparing an oil-in-water emulsion from monomers,
free-radical initiator, protective colloid and the pesticide to be
encapsulated, and triggering the polymerization of the monomers by
heating and, where necessary, controlling the polymerization by
further increasing the temperature.
29. The process according to claim 28, where, after the capsule
formation, an afterpolymerization is triggered with salts of
peroxodisulfuric acid as free-radical initiator.
30. A method for controlling phytopathogenic fungi, undesired plant
growth, or undesired insect or mite infestation, or for regulating
the growth of plants, comprising allowing the formulation of claim
16 to to act on the pests, their habitat or the plants to be
protected from the pest, the soil or on the undesired plants, the
useful plants, or their habitat.
31. The method of claim 30, wherein monomer III is selected from
the group consisting of itaconic acid, maleic anhydride,
2-hydroxyethyl acrylate and methacrylate,
acrylamido-2-methylpropanesulfonic acid, methacrylonitrile,
acrylonitrile, methacrylamide, N-vinylpyrrolidone,
N-methylolacrylamide, N-methylolmethacrylamide, dimethylaminoethyl
methacrylate and diethylaminoethyl methacrylate.
32. The method of claim 30, wherein monomer I comprises both
C.sub.1-C.sub.24-alkyl esters of acrylic acid and methacrylic acid
(monomers Ia) and further comprises one or more unsaturated
C.sub.3-C.sub.4-carboxylic acid (monomers Ib).
33. The method of claim 32, wherein the weight ratio of monomer Ia
to monomer Ib is in the range from 10:1 to 1:10.
34. The method of claim 30, wherein the polyvinyl monomer is
selected from the group consisting of trimethylolpropane
triacrylate and trimethacrylate, pentaerythritol triallyl ether,
pentaerythritol tetraallyl ether, pentaerythritol triacrylate and
pentaerythritol tetraacrylate, and their technical-grade
mixtures.
35. The method of claim 30, wherein the nonpolar solvent is soluble
in water at 20.degree. C. to at most 10% by weight.
Description
[0001] The present invention relates to microcapsules comprising a
pesticide-containing capsule core and a capsule wall, and also to a
process for the preparation of these microcapsules. Furthermore,
the invention relates to an agrochemical formulation comprising the
microcapsules, and to the use of the microcapsules for controlling
phytopathogenic fungi and/or undesired plant growth and/or
undesired insect or mite infestation and/or for regulating the
growth of plants. Combinations of preferred features with other
preferred features are encompassed by the present invention.
[0002] Agrochemical active ingredients can be encapsulated by means
of highly diverse methods. Thus, the capsule coatings can be based,
for example, on polyurethane, acylurea or polyacrylates.
[0003] Microcapsules comprising a capsule core and a capsule wall
that are based on polyacrylates are generally known:
[0004] WO 2008/071649 discloses microcapsules comprising a capsule
core and a capsule wall, where the capsule wall is constructed from
30-90% by weight of alkyl esters of (meth)acrylic acid and/or
(meth)acrylic acid and 10-70% by weight of a mixture of divinyl and
polyvinyl monomers.
[0005] The pending European patent application EP 09165134.9
discloses microcapsules comprising a capsule core and a capsule
wall, where the capsule wall is constructed from 50-90% by weight
of alkyl esters of (meth)acrylic acid and 10-50% by weight of a
mixture of divinyl and polyvinyl monomers.
[0006] The known microcapsules made of polyurethane or
polyacrylates have various disadvantages, such as very rapid
release of the capsule core.
[0007] It was therefore an object of the present invention to
provide pesticide-containing microcapsules which permit a slow and
uniform release of the pesticide.
[0008] The object is achieved by microcapsules comprising a
pesticide-containing capsule core and a capsule wall, where the
capsule wall is constructed from [0009] 30 to 90% by weight of one
or more C.sub.1-C.sub.24-alkyl esters of acrylic acid and/or
methacrylic acid, acrylic acid, methacrylic acid and/or maleic acid
(monomers I), [0010] 10 to 70% by weight of one or more polyvinyl
monomers (monomer II), and [0011] 0 to 30% by weight of one or more
further monomers (monomer III), which are different from the
monomers I,
[0012] in each case based on the total weight of the monomers.
[0013] The average particle size of the capsules (number-average by
means of light scattering) is 1 to 50 .mu.m. According to one
preferred embodiment, the average particle size of the capsules is
1.5 to 15 .mu.m, preferably 4 to 10 .mu.m. Here, preferably 90% of
the particles have a particle size of less than twice the average
particle size.
[0014] The weight ratio of capsule core to capsule wall is in most
cases in the range from 50:1 to 1:1, preferably from 20:1 to 2:1,
and in particular from 20:1 to 4:1.
[0015] The polymers of the capsule wall generally comprise at least
30% by weight, in preferred form at least 35% by weight and in
particularly preferred form at least 40% by weight, and in general
at most 90% by weight, preferably at most 80% by weight and in
particularly preferred form at most 75% by weight, of
C.sub.1-C.sub.24-alkyl esters of acrylic acid and/or methacrylic
acid, acrylic acid, methacrylic acid and/or maleic acid (monomers
I) in copolymerized form, based on the total weight of the
monomers.
[0016] According to the invention, the polymers of the capsule wall
generally comprise at least 10% by weight, preferably at least 15%
by weight, preferably at least 20% by weight, and in general at
most 70% by weight, preferably at most 60% by weight and in
particularly preferred form at most 50% by weight, of polyvinyl
monomers (monomers II) in copolymerized form, based on the total
weight of the monomers.
[0017] In addition, the polymers can comprise up to 30% by weight,
preferably up to 20% by weight, in particular up to 10% by weight,
particularly preferably up to 5% by weight, and at least 1% by
weight, of further monomers III, preferably monomers IIIa, in
copolymerized form, based on the total weight of the monomers.
[0018] Preferably, the capsule wall is constructed only from
monomers of groups I and II.
[0019] Suitable monomers I are C.sub.1-C.sub.24-alkyl esters of
acrylic acid and/or methacrylic acid (monomers Ia). Also suitable
are the unsaturated C.sub.3- and C.sub.4-carboxylic acids, such as
acrylic acid, methacrylic acid, or maleic acid (monomers Ib).
Particularly preferred monomers I are methyl acrylate, ethyl
acrylate, n-propyl acrylate and n-butyl acrylate and/or the
corresponding methacrylates. Preference is given to isopropyl
acrylate, isobutyl acrylate, sec-butyl acrylate and tert-butyl
acrylate and the corresponding methacrylates. In general, the
methacrylates and methacrylic acid are preferred.
[0020] Monomer I preferably comprises both monomers la and also
monomers Ib. Particular preference is given to mixtures of monomer
Ia (such as methyl methacrylate or C.sub.1-C24-alkyl esters of
acrylic acid) with methacrylic acid or acrylic acid. The weight
ratio of monomer Ia to monomer Ib is in most cases in the range
from 10:1 to 1:10, preferably from 6:1 to 1:8, in particular from
2:1 to 1:3.
[0021] According to one preferred embodiment, the microcapsule
walls comprise 15% by weight to 70% by weight, preferably 20 to 50%
by weight, of maleic acid and/or acrylic acid, in particular
methacrylic acid.
[0022] Suitable polyvinyl monomers are the polyesters of polyols
with acrylic acid and/or methacrylic acid, also the polyallyl and
polyvinyl ethers of these polyols. Preference is given to
trimethylolpropane triacrylate and trimethacrylate, pentaerythritol
triallyl ether, pentaerythritol tetraalkyl ether, pentaerythritol
triacrylate and pentaerythritol tetraacrylate, and their
technical-grade mixtures.
[0023] Suitable further monomers III are monomers which are
different from the monomers I and II. Examples are vinyl acetate,
vinyl propionate, vinyl pyridine and styrene or
.alpha.-methylstyrene. Particular preference is given to
charge-carrying or ionizable-group-carrying monomers IIIa which are
different from the monomers I and II, such as itaconic acid, maleic
anhydride, 2-hydroxyethyl acrylate and methacrylate,
acrylamido-2-methylpropanesulfonic acid, methacrylonitrile,
acrylonitrile, methacrylamide, N-vinylpyrrolidone,
N-methylolacrylamide, N-methylolmethacrylamide, dimethyiaminoethyl
methacrylate and diethylaminoethyl methacrylate.
[0024] Monomers III preferably comprise precisely one ethylenically
unsaturated group (such as vinyl or acrylic groups). Monomers III
are preferably free from di- or polyvinyl monomers; they
particularly preferably comprise at most 5.0% by weight, in
particular at most 1.0% by weight, and specifically at most 0.1% by
weight, of divinyl monomers.
[0025] Preferably, the capsule wall is constructed from [0026] 30
to 90% by weight of a mixture of monomers Ia and Ib, where the
fraction of the monomers Ib is 15 to 70% by weight, based on the
total weight of all of the monomers I, II and III, [0027] 10 to 70%
by weight of monomer II, and [0028] 0 to 30% by weight of further
monomers III,
[0029] in each case based on the total weight of the monomers.
[0030] The microcapsules according to the invention can be prepared
by a so-called in-situ polymerization. The principle of
microcapsule formation is based on the fact that the monomers, a
free-radical initiator, a protective colloid and the pesticide to
be encapsulated are used to prepare a stable oil-in-water emulsion.
Preferably, the pesticide is dissolved in the nonpolar solvent in
the emulsion. The polymerization of the monomers is then triggered
by heating and, where necessary, it is controlled by further
increasing the temperature, and the polymers that are produced form
the capsule wall which surrounds the pesticide. This general
principle is described, for example, in DE-A-10 139 171, to the
contents of which reference is expressly made.
[0031] The present invention therefore also provides a process for
the preparation of the microcapsules according to the invention in
which monomers, free-radical initiator, protective colloid and the
pesticide to be encapsulated are used to prepare an oil-in-water
emulsion, and the polymerization of the monomers is triggered by
heating and, where necessary, controlled by further increasing the
temperature.
[0032] As a rule, the microcapsules are prepared in the presence of
at least one organic or inorganic protective colloid. Both organic
and inorganic protective colloids may be ionic or neutral.
Protective colloids can be used here either individually or else in
mixtures of two or more identically or differently charged
protective colloids.
[0033] Organic protective colloids are preferably water-soluble
polymers which lower the surface tension of the water from 73 mN/m
maximum to 45 to 70 mN/m and thus ensure the formation of closed
capsule walls and also form microcapsules with preferred particle
sizes in the range from 0.5 to 50 .mu.m, preferably 0.5 to 30
.mu.m, in particular 0.5 to 10 .mu.m.
[0034] Organic neutral protective colloids are, for example,
cellulose derivatives, such as hydroxyethylcellulose,
methylhydroxyethylcellulose, methylcellulose and
carboxymethylcellulose, polyvinylpyrrolidone, copolymers of
vinylpyrrolidone, gelatin, gum arabic, xanthanum, casein,
polyethylene glycols, polyvinyl alcohol and partially hydrolyzed
polyvinyl acetates, and also methylhydroxypropylcellulose.
Preferred organic neutral protective colloids are polyvinyl alcohol
and partially hydrolyzed polyvinyl acetates, and also
methylhydroxypropylcellulose.
[0035] Organic anionic protective colloids are sodium alginate,
polymethacrylic acid and its copolymers, the copolymers of
sulfoethyl acrylate and methacrylate, sulfopropyl acrylate and
methacrylate, of N-(sulfoethyl)maleimide, of
2-acrylamido-2-alkylsulfonic acids, styrenesulfonic acid and also
of vinylsulfonic acid. Preferred organically anionic protective
colloids are naphthalenesuifonic acid and naphthalenesulfonic
acid-formaldehyde condensates, and in particular polyacrylic acids
and phenolsulfonic acid-formaldehyde condensates.
[0036] Inorganic protective colloids to be mentioned are so-called
Pickering systems, which permit a stabilization as a result of very
fine solid particles and are insoluble but dispersible in water or
are insoluble and nondispersible in water, but wettable by the
pesticide or the nonpolar solvent. The mode of action and their use
is described in EP-A-1 029 018 and EP-A-1 321 182, to the contents
of which reference is expressly made.
[0037] Preference is given to using organic protective colloids,
optionally in a mixture with inorganic protective colloids.
[0038] In general, the protective colloids are used in amounts of
from 0.1 to 15% by weight, preferably from 0.5 to 10% by weight,
based on the water phase. For inorganic protective colloids,
preferably amounts of from 0.5 to 15% by weight, based on the water
phase, are selected here. Organic protective colloids are
preferably used in amounts of from 0.1 to 10% by weight, based on
the water phase of the emulsion.
[0039] According to one embodiment, preference is given to
inorganic protective colloids and their mixtures with organic
protective colloids. According to a further embodiment, organically
neutral protective colloids are preferred. Particular preference is
given to protective colloids carrying OH groups, such as polyvinyl
alcohols and partially hydrolyzed polyvinyl acetates.
[0040] In general, polyvinyl alcohol and/or partially hydrolyzed
polyvinyl acetate are used in a total amount of at least 3% by
weight, based on the microcapsules (without protective colloid). In
most cases, at most 15% by weight of polyvinyl alcohol are used. It
is possible here to add further aforementioned protective colloids
in addition to the preferred amounts of polyvinyl alcohol or
partially hydrolyzed polyvinyl acetate. Preferably, the
microcapsules are prepared only with polyvinyl alcohol and/or
partially hydrolyzed polyvinyl acetate and without the addition of
further protective colloids.
[0041] According to a further embodiment, mixtures of organic
protective colloids such as polyvinyl alcohols together with
cellulose derivatives are preferred.
[0042] Polyvinyl alcohol is obtainable by polymerizing vinyl
acetate, optionally in the presence of comonomers, and hydrolyzing
the polyvinyl acetate with the elimination of the acetyl groups to
form hydroxyl groups. The degree of hydrolysis of the polymers can
be, for example, 1 to 100% and is preferably in the range from 50
to 100%, in particular from 65 to 95%. Within the context of this
application, partially hydrolyzed polyvinyl acetates are to be
understood as meaning a degree of hydrolysis of <50%, and
polyvinyl alcohol is to be understood as meaning .gtoreq.50 to
100%. The preparation of homopolymers and copolymers of vinyl
acetate, and the hydrolysis of these polymers to form polymers
comprising vinyl alcohol units is generally known. Polymers
comprising vinyl alcohol units are sold, for example, as Mowiolo
grades from Kuraray Specialities Europe (KSE). Preference is given
to polyvinyl alcohols and/or partially hydrolyzed polyvinyl
acetates, whose viscosity of a 4% strength by weight aqueous
solution at 20.degree. C. in accordance with DIN 53015 has a value
in the range from 3 to 56 mPas, preferably a value from 14 to 45
mPas. Preference is given to polyvinyl alcohols with a degree of
hydrolysis of .gtoreq.65%, preferably .gtoreq.70%, in particular
.gtoreq.75%.
[0043] The use of polyvinyl alcohol and/or partially hydrolyzed
polyvinyl acetate leads to stable emulsions even in the case of a
small average droplet size.
[0044] Usually, the size of the oil droplets almost corresponds
with the size of the microcapsules present following the
polymerization.
[0045] Free-radical initiators which can be used for the
free-radical polymerization reaction are the customary peroxo and
azo compounds, expediently in amounts of from 0.2 to 5% by weight,
based on the weight of the monomers. Depending on the state of
aggregation of the free-radical initiator and its solubility
behavior, it can be introduced as such, but preferably as solution,
emulsion or suspension, through which in particular small
quantitative amounts of free-radical initiator can be dosed more
precisely.
[0046] Preferred free-radical initiators to be mentioned are
tert-butyl peroxoneodecanoate, tert-amyl peroxypivalate, dilauroyl
peroxide, tert-amyl peroxy-2-ethylhexanoate,
2,2'-azobis(2,4-dimethyl)valeronitrile,
2,2'-azobis(2-methylbutyronitrile), dibenzoyl peroxide, tert-butyl
per-2-ethylhexanoate, di-tert-butyl peroxide, tert-butyl
hydroperoxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and
cumene hydroperoxide. Particularly preferred free-radical
initiators are di(3,5,5-trimethylhexanoyl)peroxide,
4,4'-azobisisobutyronitrile, tert-butyl perpivalate and dimethyl
2,2-azobisisobutyrate. These have a half-life of 10 hours in a
temperature range from 30 to 100.degree. C.
[0047] Furthermore, it is possible to add regulators known to the
person skilled in the art in customary amounts to the
polymerization, such as tert-dodecyl mercaptan or ethylhexyl
thioglycolate.
[0048] As a rule, the polymerization is carried out at 20 to
100.degree. C., preferably at 40 to 95.degree. C. A customary
process variant is a reaction temperature starting at 60.degree. C.
which is increased to 85.degree. C. in the course of the reaction.
Advantageous free-radical initiators have a 10-hour half-life in
the range from 45 to 65.degree. C., such as t-butyl perpivalate.
According to a further process variant, a temperature program is
selected which starts at correspondingly higher reaction
temperatures. For starting temperatures around 85.degree. C.,
preference is given to free-radical initiators with a 10-hour
half-life in the range from 70 to 90.degree. C., such as t-butyl
per-2-ethylhexanoate.
[0049] The polymerization is expediently carried out at atmospheric
pressure, although it is also possible to work at reduced or
slightly increased pressure, for example at a polymerization
temperature above 100.degree. C., thus about in the range from 0.5
to 5 bar. The reaction times for the polymerization are normally 1
to 10 hours, in most cases 2 to 5 hours.
[0050] One process variant according to the invention using
polyvinyl alcohol and/or partially hydrolyzed polyvinyl acetate
permits an advantageous procedure according to which dispersion and
polymerization are carried out directly at elevated
temperature.
[0051] In this way, it is possible to prepare microcapsules with a
desired average particle size, it being possible to adjust the
particle size in a manner known per se via the shear force, the
stirring speed, and its concentration.
[0052] After the actual polymerization reaction, for a conversion
of 90 to 99% by weight, it is generally advantageous to arrange for
the aqueous microcapsule dispersions to be largely free from odor
carriers, such as residual monomers and other volatile organic
constituents. This can be achieved in manner known per se by
physical means through distillative removal (in particular by a
steam distillation) or by stripping off with an inert gas. In
addition, it can take place by chemical means, as described in WO
99/24525, advantageously by redox-initiated polymerization, as
described in DE-A 44 35 423, DE-A 44 19 518 and DE-A 44 35 422.
[0053] Moreover, in order to reduce the residual monomer content,
according to one embodiment, the renewed addition of a free-radical
initiator is required, which defines the start of the
afterpolymerization. According to one preferred embodiment, after
the capsule formation, an afterpolymerization is triggered with
salts of peroxodisulfuric acid as free-radical initiator. Suitable
salts are in particular ammonium, sodium and potassium
peroxodisulfuric acid. The alkali metal salts of peroxodisulfuric
acid are water-soluble and initiate the afterpolymerization in
and/or from the water phase. The salts of peroxodisulfuric acid are
expediently used in amounts of from 0.2 to 5% by weight, based on
the weight of the monomers. Here, it is possible to meter them in
all at once or over a certain period. The temperature for the
afterpolymerization is usually 60 to 100.degree. C. The
afterpolymerization time is generally 0.5 to 5 hours.
[0054] According to this preferred embodiment with an
afterpolymerization with one or more salts of the peroxodisulfuric
acid as free-radical initiator, particularly low-odor microcapsules
are obtained. If required, the afterpolymerization can also be
carried out at even lower temperatures by adding reducing agents
such as sodium bisulfite. The addition of reducing agents can
further reduce the residual monomer content. Compared with
customary afterpolymerization initiators consisting of organic,
water-soluble peroxo or azo compounds such as Cert-butyl
hydroperoxide, the rate of decomposition of which can, where
necessary, be increased by adding a reducing agent such as ascorbic
acid, the salts of peroxodisulfuric acid exhibit in the end product
significantly lower amounts of odor carriers such as, for example,
aldehydes.
[0055] The microcapsules according to the invention can be
processed directly as aqueous microcapsule dispersion or in the
form of a powder. Preferably, the microcapsules are present in the
form of an aqueous dispersion.
[0056] The term agrochemical active ingredient (also called
pesticides) refers to at least one active ingredient selected from
the group of fungicides, insecticides, nematicides, herbicides,
safeners and/or growth regulators. Preferred agrochemical active
ingredients are fungicides, insecticides, herbicides and growth
regulators. Mixtures of agrochemical active ingredients from two or
more of the aforementioned classes can also be used. The person
skilled in the art is familiar with such pesticides, which can be
found, for example, in Pesticide Manual, 14th Ed. (2006), The
British Crop Protection Council, London. Suitable insecticides are
insecticides from the class of the carbamates, organophosphates,
organochlorine insecticides, phenylpyrazoles, pyrethroids,
neonicotinoids, spinosyns, avermectins, milbemycins, juvenile
hormone analogs, alkyl halides, organotin compounds, nereistoxin
analogs, benzoylureas, diacylhydrazines, METI acaricides, and also
insecticides such as chloropicrin, pymetrozin, flonicamid,
clofentezin, hexythiazox, etoxazole, diafenthiuron, propargite,
tetradifon, chlorfenapyr, DNOC, buprofezin, cyromazin, amitraz,
hydramethylnon, acequinocyl, fluacrypyrim, rotenone, or derivatives
thereof. Suitable fungicides are fungicides from the classes
dinitroanilines, allylamines, anilinopyrimidines, antibiotics,
aromatic hydrocarbons, benzenesulfonamides, benzimidazoles,
benzisothiazoles, benzophenones, benzothiadiazoles, benzotriazines,
benzylcarbamates, carbamates, carboxamides, carboxylic acid amides,
chioronitriles, cyanoacetamide oximes, cyanoimidazoles,
cyclopropanecarboxamides, dicarboxim ides, dihydrodioxazines,
dinitrophenyicrotonates, dithiocarbamates, dithiolanes,
ethylphosphonates, ethylaminothiazolecarboxamides, guanidines,
hydroxy(2-amino)pyrimidines, hydroxyanilides, imidazoles,
imidazolinones, inorganics, isobenzofuranones, methoxyacrylates,
methoxycarbamates, morpholines, N-phenylcarbamates,
oxazolidinediones, oximinoacetates, oximinoacetamides,
peptidylpyrimidine nucleosides, phenylacetamides, phenylamides,
phenylpyrroles, phenylureas, phosphonates, phosphorothiolates,
phthalamic acids, phthalimides, piperazines, piperidines,
propionamides, pyridazinones, pyridines, pyridinylmethylbenzamides,
pyrimidinamines, pyrimidines, pyrimidinonehydrazones,
pyrroloquinolinones, quinazolinones, quinolines, quinones,
sulfamides, sulfamoyltriazoles, thiazolecarboxamides,
thiocarbamates, thiophanates, thiophenecarboxamides, toluamides,
triphenyltin compounds, triazines, triazoles. Suitable herbicides
are herbicides from the classes of the acetamides, amides,
aryloxyphenoxypropionates, benzamides, benzofuran, benzoic acids,
benzothiadiazinones, bipyridylium, carbamates, chloroacetamides,
chiorocarboxylic acids, cyclohexanediones, dinitroanilines,
dinitrophenols, diphenyl ethers, glycines, imidazolinones,
isoxazoles, isoxazolidinones, nitriles, N-phenylphthalimides,
oxadiazoles, oxazolidinediones, oxyacetamides, phenoxycarboxylic
acids, phenylcarbamates, phenylpyrazoles, phenylpyrazolines,
phenylpyridazines, phosphinic aicds, phosphoroamidates,
phosphorodithioates, phthalamates, pyrazoles, pyridazinones,
pyridines, pyridine carboxylic acids, pyridinecarboxamides,
pyrimidinediones, pyrimidinyl (thio)benzoates, quinolinecarboxylic
acids, semicarbazones, sulfonylaminocarbonyltriazolinones,
sulfonylureas, tetrazolinones, thiadiazoles, thiocarbamates,
triazines, triazinones, triazoles, triazolinones,
triazolocarboxamides, triazolopyrimidines, triketones, uracils,
ureas.
[0057] Preferred pesticides dissolve to give a clear solution at
25.degree. C. to at least 10 g/l, preferably at least 100 g/l and
in particular at least 200 g/l, in an aromatic hydrocarbon mixture
with an initial boiling point (IBP, in accordance with ASTM D86) of
at least 225.degree. C. (such as Solvesso.RTM. 200). Particularly
preferred pesticides are metazachlor and pyraclostrobin.
[0058] The pesticide is preferably present in dissolved form in the
capsule core. This means that preferably at least 90% by weight, in
particular at least 98% by weight, of the pesticide is present in
dissolved form 24 h after the preparation of the microcapsules.
[0059] The pesticide-containing capsule core usually comprises
pesticide. Preferably, the capsule core additionally comprises a
nonpolar solvent. Suitable nonpolar solvents are soluble in water
at 20.degree. C. at most to 10% by weight, preferably to at most 3%
by weight, and in particular to at most 0.5% by weight. Examples
are aromatics, aliphatics, vegetable oils and esters of vegetable
oils.
[0060] Examples of aromatics are benzene, toluene, xylene,
naphthalene, biphenyl, o- or m-terphenyl, mono- or
poly-C.sub.1-C.sub.20-alkyl-substituted aromatic hydrocarbons, such
as dodecyibenzene, tetradecylbenzene, hexadecylbenzene,
methylnaphthalene, diisopropylnaphthalene, hexylnaphthalene or
decylnaphthalene. Also suitable are technical-grade aromatics
mixtures in the boiling range from 30 to 280.degree. C., and also
mixtures of the aforementioned aromatics. Preferred aromatics are
technical-grade aromatic mixtures in the boiling range from 30 to
280.degree. C.
[0061] Examples of aliphatics are saturated or unsaturated
C.sub.10-C.sub.40-hydrocarbons which are branched or preferably
linear, such as, for example, n-tetradecane, n-pentadecane,
n-hexadecane, n-heptadecane, n-octadecane, n-nonadecane,
n-eicosane, n-heneicosane, n-docosane, n-tricosane, n-tetracosane,
n-pentacosane, n-hexacosane, n-heptacosane, n-octacosane, cyclic
hydrocarbons, e.g. cyclohexane, cyclooctane, cyclodecane, mineral
oils comprising saturated hydrocarbons, or mineral oil subjected to
high-pressure hydrogenation (so-called white oils). Also suitable
are mixtures of the aforementioned aliphatics. Preferred aliphatics
are mineral oils.
[0062] Examples of vegetable oils and esters of vegetable oils are
rapeseed oil, soybean oil, palm oil, sunflower oil, corn kernel
oil, linseed oil, colza oil, olive oil, cotton seed oil, rapeseed
oil methyl ester, rapeseed oil ethyl ester, and mixtures of
vegetable oils, of esters of vegetable oils or of the two.
[0063] The weight ratio of nonpolar solvent to pesticide is in most
cases in the range 1:20 to 20:1, preferably 1:10 to 8:1, and
particularly preferably 1:8 to 4:1.
[0064] The invention also provides an agrochemical formulation
comprising the microcapsules according to the invention, where the
microcapsules are suspended in aqueous solution. The content of
pesticide which is present in the pesticide-containing capsule core
is in most cases 10 to 600 g per liter of agrochemical formulation,
preferably 50 to 400 g/l, in particular 80 to 300 g/l. The content
of microcapsules is in most cases 20 to 70% by weight, preferably
30 to 55% by weight, based on the agrochemical formulation. The
aqueous solution in most cases comprises at least 10% by weight,
preferably at least 30% by weight and in particular at least 60% by
weight, of water.
[0065] Furthermore, the agrochemical formulations can also comprise
auxiliaries customary for crop protection compositions, the choice
of auxiliaries being governed by the specific application form
and/or the active ingredient.
[0066] Examples of suitable auxiliaries are solvents,
surface-active substances (such as further solubilizers, protective
colloids, wetting agents and adhesives), organic and inorganic
thickeners, bactericides, antifreezes, antifoams, optionally dyes
and stickers (e.g. for seed treatment).
[0067] Suitable solvents are water, organic solvents such as
mineral oil fractions of moderate to high boiling point, such as
kerosene and diesel oil, also coal tar oils, and oils of vegetable
or animal origin, aliphatic, cyclic and aromatic hydrocarbons, e.g.
paraffins, tetrahydronaphthalene, alkylated naphthalenes and
derivatives thereof, alkylated benzenes and derivatives thereof,
alcohols such as methanol, ethanol, propanol, butanol and
cyclohexanol, glycols, ketones such as cyclohexanone,
gamma-butyrolactone, dimethyl fatty acid amides, fatty acids and
fatty acid esters and strongly polar solvents, e.g. amines such as
N-methylpyrrolidone. In principle, it is also possible to use
solvent mixtures, and also mixtures of the aforementioned solvents
and water.
[0068] Suitable surface-active substances (adjuvants, wetting
agents, adhesives, dispersants or emulsifiers) are the alkali
metal, alkaline earth metal, ammonium salts of aromatic sulfonic
acids, e.g. of lignosulfonic acid (Borresperse.RTM. grades,
Borregaard, Norway), phenolsulfonic acid, naphthalenesulfonic acid
(Morwet.RTM. grades, Akzo Nobel, USA) and
dibutylnaphthalenesulfonic acid (Nekal.RTM. grades, BASF, Germany),
and also of fatty acids, alkyl- and alkylarylsulfonates, alkyl,
lauryl ether and fatty alcohol sulfates, and also salts of sulfated
hexa-, hepta- and octadecanols, and also of fatty alcohol glycol
ethers, condensation products of sulfonated naphthalene and its
derivatives with formaldehyde, condensation products of naphthalene
or of naphthalenesulfonic acids with phenol and formaldehyde,
polyoxyethylene octylphenol ether, ethoxylated isooctyl-, octyl- or
nonyiphenol, alkylphenyl, tributylphenyl polyglycol ethers,
alkylaryl polyether alcohols, isotridecyl alcohol, fatty alcohol
ethylene oxide condensates, ethoxylated castor oil, polyoxyethylene
or polyoxypropylene alkyl ethers, lauryl alcohol polyglycol ether
acetate, sorbitol ester, lignosulfite waste liquors, and also
proteins, denatured proteins, polysaccharides (e.g.
methylcellulose), hydrophobically modified starches, polyvinyl
alcohol (Mowiol.RTM. grades, Clariant, Switzerland),
polycarboxylates (Sokalan.RTM. grades, BASF, Germany),
polyalkoxylates, polyvinylamine (Lupamin.RTM. grades, BASF,
Germany), polyethylenimine (Lupasol.RTM. grades, BASF, Germany),
polyvinylpyrrolidone and copolymers thereof.
[0069] Examples of thickeners (i.e. compounds which confer modified
flow behavior to the composition, i.e. high viscosity in the
resting state and low viscosity in the agitated state) are
polysaccharides, and also organic and inorganic layered minerals
such as xanthan gum (Kelzan.RTM., CP Kelco, USA), Rhodopol.RTM. 23
(Rhodia, France) or Veegum.RTM. (R.T. Vanderbilt, USA) or
Attaclay.RTM. (Engelhard Corp., NJ, USA).
[0070] For stabilization, bactericides can be added to the
composition. Examples of bactericides are those based on
dichlorophen and benzyl alcohol hemiformal (Proxel.RTM. from ICI or
Acticide.RTM. RS from Thor Chemie and Kathon.RTM. MK from Rohm
& Haas), and also isothiazolinone derivatives such as
alkylisothiazolinones and benzisothiazolinones (Acticide.RTM. MBS
from Thor Chemie). Examples of suitable antifreezes are ethylene
glycol, propylene glycol, urea and glycerol. Examples of antifoams
are silicone emulsions (such as e.g. Silikon.RTM. SRE, Wacker,
Germany or Rhodorsil.RTM., Rhodia, France), long-chain alcohols,
fatty acids, salts of fatty acids, organofluorine compounds and
mixtures thereof.
[0071] The agrochemical formulation according to the invention is
in most cases diluted prior to use in order to produce the
so-called tank mix. Of suitability for the dilution are mineral oil
fractions of moderate to high boiling point, such as kerosene or
diesel oil, also cool tar oils, and also oils of vegetable or
animal origin, aliphatic, cyclic and aromatic hydrocarbons, e.g.
toluene, xylene, paraffin, tetrahydronaphthalene, alkylated
naphthalenes or derivatives thereof, methanol, ethanol, propanol,
butanol, cyclohexanol, cyclohexanone, isophorone, strongly polar
solvents, e.g. dimethyl sulfoxide, N-methylpyrrolidone or water.
Preference is given to using water. The diluted composition is
usually applied by spraying or misting. Oils of various types,
wetting agents, adjuvants, herbicides, bactericides, fungicides can
be added to the tank mix directly prior to application (tank mix).
These agents can be admixed into the compositions according to the
invention in the weight ratio 1:100 to 100:1, preferably 1:10 to
10:1. The pesticide concentration in the tank mix can be varied
within relatively large ranges. In general, they are between 0.0001
and 10%, preferably between 0.01 and 1%. When used in crop
protection, the application rates are between 0.01 and 2.0 kg of
active ingredient per ha depending on the nature of the desired
effect.
[0072] The present invention also relates to the use of the
microcapsules according to the invention for controlling
phytopathogenic fungi and/or undesired plant growth and/or
undesired insect or mite infestation and/or for regulating the
growth of plants, where the microcapsules are allowed to act on the
pests in question, their habitat or the plants to be protected from
the pest in question, the soil and/or on undesired plants and/or
the useful plants and/or their habitat.
[0073] The present invention offers highly diverse advantages: the
microcapsules release the pesticide in a very uniform manner. The
pesticide is released over several days or weeks. The release lasts
longer than in the case of comparable microcapsules which also use
divinyl monomers as crosslinker in addition to the polyvinyl
monomers. The microcapsules are easy to prepare. They are readily
compatible for agrochemical application. The microcapsules allow
high loading with pesticide. As a result of the crosslinking with
polyvinyl monomers, the microcapsules have very good mechanical
stability (e.g. during stirring), and so the pesticide is not
released prematurely as early as during preparation in the tank mix
with stirring, but only slowly following application.
[0074] The examples below are intended to illustrate the invention
in more detail without limiting it.
EXAMPLES
[0075] Atlas.RTM. G 5000: Polyalkylene glycol ether, HLB value 17,
commercially available from Uniquema. [0076] Atlox.RTM. 4913: A
methyl methacrylate graft copolymer (reaction product of methyl
methacrylate, methacrylic acid and methoxy-PEG-methacrylate), 33%
by weight of polymer, 33% by weight of propylene glycol, 1% by
weight of xylene, 33% by weight of water (commercially available
from Uniquema). [0077] Attaflow.RTM. FL: Attapulgite thickener,
commercially available from BASF. [0078] Mowiol.RTM.: Hydrolyzed
polyvinyl alcohol, viscosity 12.5-17.5 mPas (DIN 53015),
commercially available from Kuraray [0079] Solvesso.RTM. 200:
Technical-grade mixture of aromatic hydrocarbons, aromatics content
>99% by volume (ASTM D1319), IBP (Initial Boiling Point)
232.degree. C., DP (Decomposition Point) 277.degree. C. (in each
case in accordance with ASTM D86), commercially available from
Exxon Mobil. [0080] MMA Methyl methacrylate [0081] MAA Methacrylic
acid [0082] PETIA A technical-grade mixture of tri- and
tetraacrylate of pentaerythritol [0083] PMMA Polymethyl
methacrylate
[0084] Unless stated otherwise, the percentages in the examples are
percentages by weight. The particle size of the microcapsule powder
was determined using a Malvern Particle Sizer model 3600E in
accordance with a standard measurement method which is documented
in the literature.
[0085] Determination of the evaporation rate: for the pretreatment,
2 g of the microcapsule dispersion were dried in a small metal dish
at 105.degree. C. for two hours in order to remove any residual
water. The weight (m.sub.o) was then determined. After heating for
one hour at 180.degree. C. and cooling, the weight (m.sub.1) was
again determined. The weight difference (m.sub.0-m.sub.1), based on
m.sub.0 and multiplied by 100 gives the evaporation rate in %. The
lower the value, the tighter the microcapsules. It must be ensured
here that comparisons in the evaporation rate should always be
carried out with comparable capsule sizes and stabilizer
systems.
Example 1
[0086] The water phase was initially introduced at 40.degree. C.;
feeds 1 and 2 were dispersed into this using a high-speed dissolver
stirrer at 3500 rpm. Addition 1 was added to the emulsion with
stirring using an anchor stirrer and the mixture was heated to
70.degree. C. over the course of 60 minutes, and to 85.degree. C.
over the course of a further 120 minutes. With stirring, feed 1 was
metered into the resulting microcapsule dispersion over 90 minutes
at 90.degree. C. and then the mixture was stirred for 2 hours at
this temperature. Feed 3 was then added, the mixtures cooled to
room temperature and feed 4 was added over the course of 80 min.
This gave a microcapsule dispersion with an average particle size
of D[4.3]=6.03 .mu.m and a solids content of 42.05%.
[0087] Water phase: [0088] 220 g of water [0089] 95 g of a 5%
strength by weight aqueous solution of methylhydroxypropylcellulose
(viscosity of 90-125 mPas, Brookfield, 2% by weight, 20.degree. C.,
20 rpm) [0090] 23.8 g of a 10% strength by weight aqueous solution
of polyvinyl alcohol (completely hydrolyzed, viscosity 12.5-17.5
mPas (DIN 53015)) [0091] 1.1 g of a 2.5% strength by weight aqueous
sodium nitrite solution
[0092] Addition 1 [0093] 0.35 g of a 75% strength solution of
t-butyl perpivalate in aliphatic hydrocarbons [0094] 0.43 g of
water
[0095] Feed 1: [0096] 88 g of metazachlor [0097] 132 g of Solvesso
200
[0098] Feed 2: [0099] 7.8 g of n-butyl acrylate [0100] 10.2 g of
PETIA [0101] 7.8 g of methacrylic acid
[0102] Feed 3: [0103] 2.7 g of a 10% strength by weight aqueous
t-butyl hydroperoxide solution
[0104] Feed 4: [0105] 0.15 g of ascorbic acid [0106] 14.0 g of
water
Example 2
[0107] The procedure was analogous to example 1, except feed 2
consisted of the following components:
[0108] Feed 2: [0109] 7.8 g of methyl methacrylate [0110] 10.2 g of
PETIA [0111] 7.8 g of methacrylic acid
[0112] This gave a microcapsule dispersion with an average particle
size of D[4,3]=6.04 .mu.m and a solids content of 42.05%.
Example 3
[0113] The procedure was analogous to example 1, except feed 2
consisted of the following components:
[0114] Feed 2: [0115] 16.5 g of methyl methacrylate [0116] 22.0 g
of pentaerythritol triacrylate (PETIA) [0117] 16.5 g of methacrylic
acid
[0118] At the end, the mixture was neutralized with aqueous sodium
hydroxide solution. This gave a microcapsule dispersion with an
average particle size of 4.84 .mu.m (D4,3) and a solids content of
45.76%. The evaporation rate at 130.degree. C. (1 h) was 4.3%.
Example 3
[0119] The procedure was analogous to example 1, except feed 2
consisted of the following components:
[0120] Feed 2: [0121] 5.16 g of methyl methacrylate [0122] 10.32 g
of pentaerythritol triacrylate (PETIA) [0123] 10.32 g of
methacrylic acid
[0124] At the end, the mixture was neutralized with aqueous sodium
hydroxide solution. This gave a microcapsule dispersion with an
average particle size of 6.71 .mu.m (D4,3) and a solids content of
42.45%. The evaporation rate at 130.degree. C. (1 h) was 13.5%.
Example 4 (Comparative Example, Not According to the Invention)
[0125] The procedure was analogous to example 1, except in feed 2
pentaerythritol triacrylate (PETIA) was replaced by the same amount
of butanediol diacrylate. This gave a microcapsule dispersion with
an average particle size of D[4,3]=7.60 .mu.m and a solids content
of 42.05%.
Example 5 (Comparative Example, Not According to the Invention)
[0126] The procedure was analogous to example 2, except in feed 2
pentaerythritol triacrylate (PETIA) was replaced by the same amount
of butanediol diacrylate. This gave a microcapsule dispersion with
an average particle size of D[4,3]=8.02 .mu.m and a solids content
of 42.05%.
Example 6 (Comparative Example, Not According to the Invention)
[0127] The procedure was analogous to example 4, except in feed 2
pentaerythritol triacrylate (PETIA) was replaced by the same amount
of butanediol diacrylate. This gave a microcapsule dispersion with
an average particle size of 6.61 .mu.m (D4,3) and a solids content
of 42.07%. The evaporation rate at 130.degree. C. (1 h) was
30.18%.
Example 7
Release of the Pesticide
[0128] An amount of the microcapsule dispersion from the
aforementioned examples which comprised 300 mg of metazachlor was
weighed in and topped up to 1.0 l with distilled water (=ca. 75% of
the maximum soluble amount of metazachlor in 1 l of water) and
stirred at room temperature. Here, good mechanical stability was
exhibited since no metazachlor was released from stirring, as the
very low starting values in tables 1-4 indicate.
[0129] In each case 5 ml of the resulting diluted mixture was
removed at different time intervals and was filtered over a 0.22
.mu.m filter and the metazachlor content was determined
photometrically by means of UV-VIS spectroscopy with the help of a
calibration curve. In order to make sure that no impurity disturbed
the measurement, the absorption was determined at different
wavelengths. The content of metazachlor in the aqueous solution
determined in this way is summarized in table 1. The values show
how much metazachlor was released from the microcapsules into the
aqueous phase.
TABLE-US-00001 TABLE 1 Example 5 Comparative example 9 Time [h]
Release [%] Release [%] 0.5 10 86 1 12 92 2 13 98 4 17 100 8 19 100
24 26 100 48 26 100 72 29 -- 192 50 100 384 58 -- 744 68 -- 1536 76
--
TABLE-US-00002 TABLE 2 Example 6 Comparative example 10 Time [h]
Release [%] Release [%] 0.5 -- 19 1 1.3 24 4 1.6 36 8 1.9 40 24 2.3
46 48 2.6 54 192 3.7 76 384 5.0 83 792 5.1 --
TABLE-US-00003 TABLE 3 Example 8 Comparative example 11 Time [h]
Release [%] Release [%] 1 10 22 4.5 13 36 8 14 43 24 16 56 96 27 81
192 24 85 360 29 92 768 41 100 1536 50 --
TABLE-US-00004 TABLE 4 Example 7 Time [h] Time [days] Release [%] 4
0.17 4 7 0.29 5 24 1 6 48 2 7 120 5 12 192 8 10 384 16 11 792 33 27
1536 64 40 3072 128 49
Example 8
[0130] The microcapsules A and B were prepared with the
concentrations according to table 5. The water phase comprising
water, protective colloid and sodium nitrile was prepared. The oil
phase was prepared by dissolving pyraclostrobin in Solvesso at
elevated temperature, and then adding it to the water phase with
stirring. The monomers were then added. The two-phase mixture was
stirred at 70.degree. C. for 30 min and cooled to 50.degree. C. The
resulting emulsion was admixed with t-butyl perpivalate with
stirring and heated at 70.degree. C. for 2 h and then held at
85.degree. C. for 1.5 h. t-butyl hydroperoxide and ascorbic acid
were then added over the course of 60 min while the mixture was
cooled to 20.degree. C. The suspension of pyraclostrobin-containing
microcapsules obtained in this way could be further used without
further work-up.
TABLE-US-00005 TABLE 5 Formulations (concentration in g/l) A B
Pyraclostrobin 250 250 MMA 24 19.2 MAA 24 19.2 PETIA 32 25.6
Ascorbic acid 0.1 0.08 Atlas G 5000 0 6.64 Atlox 4913 0 6.64
Attaflow FL 0 4.28 Antifoam 0 0.22 Mowiol 321.8 257.4 Sodium
nitrite 2.8 2.24 Solvesso 200 64 51.2 t-Butyl peroxypivalate 0.57
0.46 t-Butyl hydroperoxide 18.4 14.72 Water ad 1000 ml ad 1000
ml
* * * * *